PEOCEEDINGS OF THE MALACOLOGICAX SOCIEir. 201 



The following papers were read : — 



1. "Oil a new species of Plectotropis from Burmah," by E. A. 

 Smith, F.Z.S. 



2. " Descriptions of new species of Pleurotoma, Mitra, and Latirus,''^ 

 by J. C. Melvill, M.A., F.L.S. 



3. "Descriptions of two new species of Terrestrial Mollusca from 

 the Hadramaut District, S. Arabia," by J. C. Melvill, M.A., F.L.S. 



4. " Notes on the anatomy of BuUminus Procter i, Sow., and 

 JBulimulus Kopelli, Sow.," by S. Pace. 



Dr. H. Woodward exhibited opalized specimens of a tooth of 

 Polyptychodon, the guard of Belemnitella, and a bivalve shell, from 

 "New South AVales. 



Mr. J. C. Melvill exhibited a reversed specimen of Helix hcemastoma, 

 Linn., and specimens of Voluta Prevostiana^ Crosse, and Rostellaria 

 Martinii, Marrat. 



Mr. E. A. Smith exhibited some remarkable deep-water Molluscs 

 from the Indian Ocean. 



Mr. G. B. Sowerby exhibited a series of specimens of Trigonia 

 belonging to the three species, T, margaritacea, Lamk., T. Lamarckii, 

 Gray, and T. dubia, Sow. 



Mr. T. H. Haynes exhibited, and made some remarks on, specimens 

 illustrating pearl-growth. 



[abstract.] 



He stated it was now generally recognized by Pearlers, that pearls 

 were formed within the tissues of the mollusc, and on escaping came 

 between the animal and its shell, where they were treatecl like any 

 other foreign body, and either ejected or became attached to the shell 

 by the next layer of shelly matter secreted. The formation of 

 "blisters" on the interior of the Meleagrina valves, was due to the 

 endeavour of the animal to coat over with shelly matter any foreign 

 body, which it was unable to eject, such as a dead pea-crab, or a 

 shell, or an attached pearl. Blisters were also formed over the point 

 where any boring mollusc had burrowed into the valve and threatened 

 to perforate it. One diver he knew was able to predict with singular 

 accuracy which shells would be likely to contain pearls, either free 

 or attached, and which would contain nothing. This the man 

 explained by asserting that the two sides of the hinge in those shells 

 containing pearls were not exactly parallel. 



Pearls sometimes became united together either in pairs or clusters : 

 a less common phenomenon was their attachment in the form of a 

 cross, as in the celebrated " Southern Cross," and in a second specimen 

 since found, which he exhibited. 



Mr. S. Pace exhibited spirit specimens of Aphjsia, Trigonia, and 

 Ahralia Owenii, Verany, showing the luminous organ ; also micro- 

 scope slides relating to the Aptychus. 



Mr. H. Fulton exhibited specimens of Voluta concinna, Brod., and 

 Palaina mirabile, Mollcndorii, from the Philippines. 



Mr. E. P. Sykes exhibited specimens of Littorina rudis, Maton., 

 from Dorset. 



